For years, doctors and health experts have tried in vain to douse the modern anti-vaccine movement with data and science. They’ve showered vaccine-hesitant parents with data on the safety and efficacy of the life-saving injections, plus information on herd immunity and the dangers of otherwise bygone diseases, such as measles. Nevertheless, the efforts largely fail. In some cases, they even backfire; mind-boggling studies have found that repeating myths and misinformation in the process of debunking them can actually reinforce them.

For a new tactic, public health researchers have turned away from facts and reason and toward morals and values. They hypothesized that if they can pitch vaccines in a way that gives anti-vaccine parents all the right feels, they may finally quench the insidious and deadly movement. And indeed, in a preliminary study, they found evidence that vaccine-averse parents have differing moral foundations than those who embrace vaccines.

In the initial study of 1,007 parents, researchers found that the most vaccine-hesitant parents were twice as likely as low-hesitancy parents to place high value on ideals of "purity" and "liberty." Those are two of six value categories in the Moral Foundation Theory, which social psychologists developed years ago to untangle people’s moral judgments and decisions based on emotional or intuitive processes—not data and science.